平行四边形是一种特殊的四边形,它的对边平行且相等,对角相等,对角线互相平分.许多几何问题可以通过构造平行四边形,应用它们边、角、对角线性质,达到求证(解)的目的.今举几例,以开阔同学们的视野.例1如图,图1、图2、图 Parallelogram is a special type of quadrilateral that is parallel and equal to one another, equal in diagonal, and diagonally equal to each other. Many geometric problems can be solved by constructing parallelograms that apply their edge, angle, and diagonal properties Solution) purposes. Now a few examples to broaden the horizons of students. Example 1 Figure 1, Figure 2, Figure